BBS02 750w on 52v 18650?

[RVD]

I am thinking of building a new battery pack for my BBS02 750w. It is currently set for 48v which all I think means that it has a LVC set for 41v. I can look into changing this or I don't care...I always monitor my own voltage usage with a watt meter on my bike anyway.

I am currently using lipo and running it at 12s1p (44v 5ah). I have a relatively short 8 mile commute and this pack is able to handle each way very easily (I usually end up using about 2.5-3ah worth of battery). I charge at work using a very slow charger. i use an imax b6ac which is only 50 watts so it takes around 4 hours or so to charge up this pack at work but I am not in any rush and I want it to be safe (don't want a fire at work in the bike cage).

For my 18650 pack I am using Sony US18650V3 cells. I believe that these are lithium manganese cells and each cell is 2150-2250ah. I am thinking of building a 14s3p pack so it will be a 52v pack but probably closer to 58v or so hot off the charger.

At 25 amp, this would be pushing a peak of 1450 watts. I am assuming that my motor will not like this for any sustained period of time but my commute mostly flat and downhill with the only exception of one very big monster hill at the end of my commute when I am coming home. So even if I start out at a high voltage, by the time I am near home on this big hill (>20% grade), I'm guessing I'll be at around 52v so 1300 watts and will be at that max wattage for maybe around 5 minutes.

On my smaller 44v lipo setup, the motor seems to handle 1100 watts (with me pedaling) going up that big hill just fine. Anyone know if it can handle 1300 watts ok?

I have not done any modifications to my BBS02. I bought it from luna late last year so I'm not sure if it has the updated controller mosfets or not.

 

[rs4race]

Luna seems to recommend 52v packs for the bbs02. You can reprogram the controller to cutoff at 43v or use a bms. I think if you just don't leave it in a high gear and bog down the motor going up the hill you will be ok.

https://www.electricbike.com/bafang-750w-bbs02/

 

[FastJohnny]

If you go with a 3P pack, make sure to use Samsung 25R cells. If you can step up to 4P you can get away with a cell that can only provide 10A per cell like the newer GA cell, or a PF cell.

You'll never actually pull 1450 watts with a 3P or even 4P pack. You're going to get voltage sag under full throttle when you pull max amps. For example, when I pull 60A through my freshly charged 58.8V 14S7P 70A max PF pack the voltage will sag all the way down to 52V, and then jump back up to 58.8V when I let off. I'm not 100% certain but I believe the voltage sag is not as bad if you're not approaching max amps. In other words you'll have less voltage sag pulling 25A off a 14S8P 25R pack with cells rated to 160A in an 8P config, than you would pulling 25A off a 3P setup rated for 30A.

You'll definitely notice a difference in power running 58V on a pack that can sustain 25A.

 

[RVD]

ok i'll try this on 14s lipo first to see how performance it is before building the 18650 pack.

i just use normal turnigy 20c lipos. i know that the c rating is grossly overrated but even if i only run some small 5ah batteries (so 14s1p using 5ah lipos), would that cause any problems? even at 25a which would be at burst and only for a short time, it would be 5c. usually the bike seems to use more like 1-5ah (so <1c) but when I go up hills it pulls 15-25 amps for 1-2 minutes.

 

[Clientti]

I borrow this...

My question is, is it possible to use my 36v bafang 250w (upgraded to 18A) with 48v battery. Will i fry my motor or controller?

I believe battery packs does have bms, so voltage cut off shouldnt be problem?

WIll i encounter any problems? I am planning to put a lot smaller chain ring.

 

[Clientti]

Anyone?

 

[Raged]

ok i'll try this on 14s lipo first to see how performance it is before building the 18650 pack.

i just use normal turnigy 20c lipos. i know that the c rating is grossly overrated but even if i only run some small 5ah batteries (so 14s1p using 5ah lipos), would that cause any problems? even at 25a which would be at burst and only for a short time, it would be 5c. usually the bike seems to use more like 1-5ah (so <1c) but when I go up hills it pulls 15-25 amps for 1-2 minutes.

I run 14s1P of zippy compact 25c 5800mah on my BBS02. It's fine for a 30km commute on a cyclocross and keeps the weight down for nimbleness.